We investigated the effects of different application rates of insoluble hydrophilic polyacrylate polymers
on plant growth and soil quality from a Pb-contaminated mine soil. The polymer increased the waterholding
capacity of the soil from about 250 g ⁄ kg in unamended soil to almost 1000 g ⁄ kg in soil with
0.6% polymer. However, the capacity of the polymer to retain water decreased progressively, presumably
as the polymer sorbed Pb. Growth of orchardgrass (Dactylis glomerata L. cv. Amba) was stimulated
in the polymer-amended soil. The greatest accumulated biomass over four cuts was obtained in
soil amended with 0.4% of polymer. After orchardgrass had been growing for 101 days, the amounts
of CaCl2-extractable Pb present in the polymer-amended soil were 15–66% of those in the unamended
soil, depending on polymer application rate. The number of bacteria culturable on agar enriched with
‘Nutrient’ and yeast extract, and the activities of dehydrogenase, phosphatase, b-glucosidase, protease
and cellulase increased following polymer application. In contrast, urease activity was impaired by
polymer application, presumably due to the presence of ammonium as a counter ion. Principal component
analysis was used to compare the effects of the different rates of polymer application. Overall,
the application of 0.2 or 0.4% polymer resulted in closer values for the indicators of soil quality used
than the treatment with 0.6% polymer.